Transformer employed in high-frequency-current circuits.



N0 877,319. PATENTED JAN. 2l, 1908. G. B. GAIFFE. TRANSFORMER EMPLOYED IN HGH FREQUENCY CURRENT CRGUITS.

APPLICATION FILED NGV. 8. 1904.

eEoRGEs EUGENE GAIFFEQOF PAEiarRANcE.

TRANSFORMER EMrLoYED 1N lnre'1r-EREerinner-cuartaNT craouirs.

Specication of Letters Patent.

Patented Jan. 21, 1908.

apprenante November 811904. serai No. 231.892.

VTo vall 'whom 'it may-concern:

Be it knownthat I, GEORGES EGNE GAIFFE, of @"Ru'e Mchaim in the city of Paris, Republic 'of France, electricaLengineer, have invented Improvements in or Connected with Transformers Employed in High-Frequency-Current Circuits, of which the following is a full, clear, and exact description.

High potential transformers, alternating current transformers, Ruhmkorif coils, etc, and in general any source of continuous or alternating current which are em loyed in a circuit producing oscillations ofJ high frequency are themselves traversed by currents of high frequency since the secondary of a transformer-"1s itself'a capacity which charges anddischarges in accordance with the oscillations takinglplace in the main high frequency circuit. tions are produced within the secondary of the transformer and these spread lengthwise of the Winding atacertainvelocity. From this it results that at the same instant, two

adjacent points of the Winding may be at very different potentialsand this difference of potential may amount tothe total difference of potential of the transformer. A high potential transformer is thus incapable of working at high frequency, unless. special precautions are taken.

The present invention has 'for its object to Y provide means whereby the above mentioned disadvantage may be remedied.

This invention consists essentiallyin the l employment, with the object of damping thel oscillations of high frequency which tend to traverse th'e said transformer, of resistances either alone or in conjunction with capacities connected to the extremities ofthe secondary of the transformer.

' The accompanying drawing diagrammatically illustratesthe principle of the invention, by way of example.

Figure 1 illustrates an apparatus serving to explain the` phenomenon to which are-due the dangers \peculiar to the working of sources of high potential owin to the production of oscillations of hig frequency.

Fig. 1'c1 shows. the resistances applied to the.V

two extremities of the secondary within the transformer itself. Fig. 2 shows the resistlances applied to the two extremities of the secondary outside the transformer. Figs. 3

and 4 show similar arrangements of the reence electric oscilla- Fig. 5 shows-a modification of for protecting the apparatus against extreme differences in potential.-

The same letters of reference indicate the same parts in the several ii ures.

sistancesand in addition the capacities above" referred to. Fi 4. Fig. 6 is a section taken through. a- Acel showing' indetail one of the resistances Referring `to Fig. 1, which serves to ex.- I

plain the phenomenonwhich takesy place, a is the secondary winding of a high potential transformer; d is the high-frequency instalf lation. The point n of the 'spark-gap circuit follows the variations of potential produced by the oscillating discharge of the condensers of circuit d. Thus if the source has charged the. plate h of condenser i to a otential of +100,000 volts, that the periodicity of the -oscillations in the circuit d is one million, this shows, supposing the damping of the electric oscillations to be ntl, that the point n passes from the potential 100,000 volts to the potential 100,000 volts With a frequency of 1,000,000 cycles per second, n being the extremity of the winding a of the transformer.

The primary winding p is used to energize the secondary winding by induction .in the usual manner. While these oscillations are being produced the source tends to maintain at the extremities of the transformer a potential which may be considered as constant during a short interval of time, which potential -is -l- 100,000 volts; thus there is at certain moments a potential of 100,000 volts at one of transformer termi1ials ,wvhile the source tends to maintain the potentialthereat, at -l-l00,000 volts. lf we consider a point m situated in one of the last coils'of the winding a, it is suchthat the self-induction of circuit m, n is `sufficient to prevent the rapid varia.- tions of difference of potential from 100,000 to 100,000 volts at the one terminal of the spark gap fromiaff'ecting the potential of the point m which remains at a potential .of +100,000 volts, less the feeble electro-motive force due to the winding m, n. Between the points m and n 'there are thus inioo stantaneous differences of potential of from +100,000 to 100,000 vous, or 200,000 volts, that is to say the total potential-difference of the transformer and this constitutes of the secondary a of the transformer, or

windings l), c (sufficiently well insulated to withstand the high pressuresbroughtfintoi play) having a resistance ca able of damping the ,highfrequency osci ationsfwhatever may be their wave length land consequently i of keeping lthe dangerous portion comprised A between the extremity n (Fig. l) lof the transriations of potential ofthe spark gap. d informer and point in, independent o f the vadicates the hi h-frequency circuit. rlhe resistance and t e insulation of'the windings ondary.

b, c may be obtained in any suitable manner, as for example by the alternate or inter-winding of a wire of high resistance with any suitable insulating material. The secondary of the transformer thus comprises at each of its extremities a winding whose resistance and insulationA are of much greater value than those required in ordinary industrial appli-l iiciently well insulated to prevent sparking between any two oints of the resistances. To each resistance c there may be connected a capacity @fas shown Figs. 3 and 4, which is supplemental to the capacity of the transformer winding itself. e, f, may be of any suitable vkind an are so connected that the charging oscillations will tend to traverse the resistance Whatever may be the position-of this resistance relatively tothe transformer. Fig. 3shows the arrangement of the vcapacities e, f inthe case when the safety-resistances are placed in the interior of the transformer, while Fig. 4 shows the arrangement when the resistances areA placed externally to the transformer. The

addition of this capacity permits either, with a given resistance, of augmenting the d amping effect produced by this resistance or (if a stated amount ofdamping is rendered necessary by the conditions ofworking), of diminishing the resistance necessary for producing such damping.

Fig. 5 represents a modiiicationbf Fig. 4.

'Ihe capacities e, f (Figs. 3 and 4) in .this arrangement consist of any suitable condenser g sufliciently well insulated. The function of the capacity inthe arrangements shown in Figs. 4 and 5 may be explained'a's follows:

I 'The capacities e, f (Figs. 3, 4 and 6) are difference of potential as that of the source. 1n

'cated in Fi 5.

grounded as shown. Instead of 'these capaci.- ties I sometimes use a condenser g, as indi- The capacities or the condenser, as t e case maybe, serve as a reservoir which becomes charged to the same and this reservoir can only discharge itself- These ca acities` lslowly through the windings I) and c, so that when point f/L of the spark-gap passes to the potential 100,000 volts (to revert to thefigures before mentioned), the potential of thepoint nl varies but very little inasmuch as' the condenser g can only dischargebut "a' Very small quantity during the millionth of a second during whichtlle oscillationexists,

andconsequently between the point 'm (seeY description of Fig. 1) and point n1 only such slight dierences of otential will exist as will exclude all possiliiility of danger to the insulation. v

It is'to be observedthat the resistance may be replaced by self-inductive devices orby the combination of resistance and self-induction, and generally by any means of retarding the discharge. of the condensers. f and damping the return' oscillations. ""1- i The safety device of this invention is suitable. for use 'with all high-potential 'transformer's, alternating-current transformers, Ruhmkorff coils, etc., and generally with any source of supply of a continuous oralternating current employed in circuits .inwhichoscillations of'high frequency are liable to vbe produced, either continuously (as in wireless telegraphyandl medical coils) or interlmittently as industrial installations.

Claims. y Y' 1. The combination ofv anhoscillationlcircuit, .a secondary Winding for energizing the same, and means for protecting said secondaryF winding from potential strains accumulating within said oscillation circuitgfV 2. The combination of an oscillation circuit, a secondary winding for energizing the same, and resistances inserted intermediate of said oscillation circuit and said secondary windingfor protecting the latter from potentialstrains of said oscillation circuit.

3. The combination of an oscillation circuit, a secondary winding for energizing the same, resistances inserted intermediate of said oscillation circuit and said secondary winding andpreventing disruptive .discharges from taking place from said oscillation circuit to said secondary winding, and condensers for deadening the electric oscillations tending to take place inthe secondary winding and capable of producing said disruptive discharges.

4. The combination of an oscillation vcircuit, a secondary Iwinding disposed in conductive relation thereto and resistances connected at the ends of said secondary winding, and high potential insulation for preventing the escape of current from said resistances.

. 5. A safety device for protecting high 'potential transformers against orcillation of high frequency, comprising a secondary winding, resistances connectedwith the'ends thereof, electric capacities joined intermediate said resistances and said secondarg.T windg. 6. A safety device for protecting high potential transformes egainst oscillation of formels employed in high equcncy current high frequency, comprising a secondary circuits signed by me this 24th dey of Winding provided With end,leslsances,` and October, 190%.

electric capacities disposed intermediate seid i GEORGES EUGNE GAFFE. 5 end resista-Does and the secondary wlndlng. j 'Titnesses2 The foregoing .specification oi my Ini- BL'LTHIEU AMBnoIsE GUIRAUF,

proveniente in or connected with trans- MAURICE H. PIGNET. 

